1. Technical Field
The present invention relates to a liquid ejection head unit having a liquid ejection head for ejecting liquid, and to a liquid ejection apparatus.
2. Related Art
JP-A-2005-289074 discloses a liquid ejection head having a flow-path forming substrate that forms pressure generating chambers communicating with nozzle openings, and an ink storage chamber, which serves as a manifold, i.e., an ink chamber, common to the pressure generating chambers. A nozzle plate provided with a plurality of nozzle openings is bonded to one surface of the flow-path forming substrate. A liquid ejection head unit includes a liquid ejection head like this.
A vibration plate is bonded to the other surface of the flow-path forming substrate, and piezoelectric vibrators, which serve as piezoelectric elements that change the pressure in the pressure generating chambers to discharge ink from the nozzle openings, are disposed so as to face the pressure generating chambers with the vibration plate therebetween. The vibration plate is made of a metal film and a resin film bonded together. Furthermore, a protection substrate for protecting the piezoelectric vibrators, a case head, etc., is provided on the other surface of the flow-path forming substrate.
A flexible wiring substrate is bonded to lead electrodes extending from the piezoelectric vibrators with an anisotropic conductive adhesive, such as an anisotropic conductive film (ACF) or an anisotropic conductive paste (ACP), in which conductive particles are dispersed in resin. The flexible wiring substrate, which extends through the case head, is connected to a control unit via a driving IC for the piezoelectric vibrators and a terminal of a connecting substrate.
A damper recess for absorbing pressure fluctuation in the manifold is provided in the case head or the like via the vibration plate, and the damper recess communicates with the outside through an external communication path formed in the case head or the like. Herein, an opening of the external communication path is provided so as to face a direction in which the flexible wiring substrate extends.
Furthermore, liquid, which contains solvent, is introduced into the manifold through a liquid introduction path.
However, because the opening of the external communication path is provided so as to face the direction in which the flexible wiring substrate extends, the liquid solvent reaches a connecting portion of the lead electrodes and the flexible wiring substrate through the opening, through which the flexible wiring substrate extends, and a space in which the flexible wiring substrate is stored, decomposing or swelling the resin used in the ACF or the like and causing poor contact at the connecting portion. Furthermore, if the opening of the external communication path is provided in a side surface of the case head or provided so as to face the nozzle plate, that is, provided in a direction different from the direction in which the flexible wiring substrate extends, liquid ejected from the nozzle plate easily enters the opening. As a result, the liquid blocks the external communication path, making it difficult to absorb pressure fluctuation in the manifold.